The present invention relates to alternators or to alternator-starters.
A vehicle alternator is known that comprises a case, a stator winding, and a solidified electrically-insulating varnish impregnating the end turns and the twisted leads of the winding so as to insulate them electrically from the adjacent case and so as to reinforce their mechanical strength. The neutral points of the winding are insulated in the same manner. Nevertheless, when subjected to the vibration due to operation, there is a major risk of the varnish being abraded and thus of the electrical insulation of the end turns, the twisted leads, and the neutral points disappearing.
U.S. Pat. No. 4,658,165 discloses a vehicle alternator in which an electrically-insulating screen is provided in the form of a separate piece extending between the stator winding and the case. That avoids the risk of abrasion. However, that patent provides for the twisted leads to be returned along the screen and complicates connection thereof.
An object of the invention is to ensure that the insulating protection is long-lasting without complicating the connection of the twisted leads.
To achieve this object, the invention provides a vehicle alternator comprising a case, a stator winding, and an electrically-insulating element interposed between the case and the winding, the insulating element being a solid body mounted on one of the case and the winding, wherein the insulating element has at least one duct extending through an orifice in the case.
There is thus no risk of abrasion of the insulating element and as a result the protection is long-lasting.
In addition, the duct can receive a twisted lead of live outlet wires from the winding, which twisted lead is thus electrically insulated from the case where it passes through the case, e.g. at the back plate of the case. In addition, the duct can receive the twisted lead before being installed in the case, thus making it possible to guarantee the position of the twisted lead relative to the winding, e.g. a rectilinear position, prior to being received in the case.
Advantageously, the duct extends from a front face of the insulating element.
Advantageously, the duct extends so as to project from an inner side face of the insulating element towards an axis of the stator.
Thus, the duct is suitable for an arched twisted lead, i.e. one which does not leave the stator in register with a slot in the stack of laminations but is offset so as to be better placed, given the design of the electronic portion of the alternator, e.g. situated at the rear of the case.
Advantageously, the or each duct receives a live wire twisted lead of the winding.
Advantageously, the insulating element is interposed between the case and the winding radially relative to an axis of the stator.
Advantageously, the insulating element is interposed between the case and the winding axially relative to an axis of the stator.
Advantageously, the insulating element extends in register with an inner side face of the winding.
Advantageously, the insulating element has an indexing portion, in particular a stud, enabling the angular position of the stator around an axis of the stator to be identified.
Thus, the angular position of the stator about its axis is identified, making it easier to install, and guaranteeing that the twisted leads of live wires are properly positioned relative to the case, and in particular relative to the orifices therein.
Advantageously, the case has a second indexing portion, in particular a groove, suitable for cooperating with the indexing portion of the insulating element.
The invention also provides a method of manufacturing a vehicle alternator comprising a case, a stator winding, and an electrically-insulating element interposed between the case and the winding, wherein: the insulating element is supplied in the form of a solid body having at least one duct; the insulating element is mounted on one of the case and the winding; and the duct is inserted through an orifice in the case.
Advantageously, the insulating element is mounted on the winding.
Advantageously, the insulating element is mounted on the case.